1. Field of the Invention
The present invention relates to a valve opening/closing handle lock mechanism of a valve or shut-off cock, and more particularly to a valve opening/closing handle lock mechanism of a valve or shut-off cock, wherein the handle lock mechanism is provided in a valve or shut-off cock of a type incorporated in a flow passage of a fluid such as water, a liquid chemical, a gas and the like, wherein the valve opening/closing handle lock mechanism is manually operated to open and close the flow passage, and prevents the valve or shut-off cock from being opened or closed by accident or with malicious intent after completion of a proper opening/closing operation of the valve or shut-off cock.
2. Description of the Related Art
Used in various types of plants are various types of valves or shut-off cocks for opening/closing a flow passage of a fluid such as water, a liquid chemical, a gas and the like. Each of these valves or cocks is manually operated by means of a valve opening/closing handle. In the valve opening/closing operation of each valve or cock, the valve opening/closing handle is turned or rotated horizontally or vertically relative to a main body of the valve or shut-off cock (hereinafter referred to as the valve).
In installation, the valve is projected from the fluid passage or circuit outward. Due to this, there is a fear that: a worker moving along the fluid circuit is accidentally brought into contact with a valve opening/closing handle of the valve; and, performs a valve opening/closing operation of the valve by mistake. Further, since it is possible for anyone to perform a valve opening/closing operation of a conventional type of the valve (see Japanese Patent application Laid-open No. 2002-147646), there is a fear that the valve is operated with malicious intent or improperly operated by a person not skilled in the art after completion of a proper opening/closing operation of the valve. Consequently, up to the present day it is hard to keep the security of the valve.
As described above, in the conventional manually-operated valve provided with the manually-operated valve opening/closing handle, there is a problem or fear that: the valve opening/closing handle of the valve is accidentally or improperly operated by mistake or by accident, or operated with malicious intent after completion of a proper opening/closing operation of the valve, which makes it hard to keep the security of the valve in operation.